[aaronbaugher]

That's how it used to work. But people noticed that some groups got held back at higher rates than others, and there were accusations of isms, and so most schools decided it would be better for everyone involved to stop doing that. Also, holding a kid back came to be seen as cruel since the other kids would make fun of him, which was probably true.

For the same reason, they mostly got rid of "tracks," where an age group would be divided into different classrooms according to test scores and previous grades rather than random chance, so the 'A' fourth grade room could go at a different pace from the 'B' fourth grade room. All that's left of that is gifted programs, which people somehow accept even though they're just the mirror image of holding kids back.

There's really not a good answer, because like it or not, learning ability varies, so if you put 25 kids in the same classroom for no reason other than their being the same age and living in the same neighborhood, some are going to struggle and fail and some are going to cruise and be bored.